I think this is a nice short example of some collaborative work written with the use of a mailing list; here is the thread where I proposed the initial SQL outline, from there it was modified then implemented:
http://www.hants.lug.org.uk/lurker/message/20090113.115628.7a17529e.en.html
GPL http://creativecommons.org/licenses/GPL/2.0/ 2.0
#---------------------------------------------------------------------------
# Hampshire Linux Users Group meeting register of attendees.
# Executed once to define database and tables with constraints.
#---------------------------------------------------------------------------
#DROP DATABASE bab_register;
CREATE DATABASE bab_register DEFAULT CHARACTER SET utf8;
USE bab_register;
DROP TABLE IF EXISTS attendee;
CREATE TABLE attendee (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(50) NOT NULL,
email VARCHAR(150),
member ENUM('yes','no') NOT NULL,
new_attendee ENUM('no','yes') NOT NULL,
PRIMARY KEY (id)
) COMMENT "HLUG BaB meeting register Southampton Uni (ECS)";
DROP TABLE IF EXISTS macs;
CREATE TABLE macs (
id INT NOT NULL AUTO_INCREMENT,
attendee_id INT NOT NULL,
mac VARCHAR(17) NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (attendee_id) REFERENCES attendee (id)
) COMMENT "MAC Address entries, more than one per attendee";